Methods and compositions for removing Group VIII metal-containing materials from surfaces

ABSTRACT

A method and composition for removing Group VIII metal-containing materials from a surface (preferably, a platinum-containing, and more preferably, a platinum-rhodium-containing surface) involves the use of a mixture of phosphoric acid, sulfuric acid, nitric acid, and hydrochloric acid.

FIELD OF THE INVENTION

The present invention relates to methods for removing Group VIIImetal-containing materials (preferably, platinum-containing, and morepreferably, platinum-rhodium-containing materials) from surfaces,particularly in the fabrication of semiconductor devices.

BACKGROUND OF THE INVENTION

Films of metals and metal oxides, particularly the heavier elements ofGroup VIII, are becoming important for a variety of electronic andelectrochemical applications. This is at least because many of the GroupVIII metal films are generally unreactive, resistant to diffusion ofoxygen and silicon, and are good conductors. Oxides of certain of thesemetals also possess these properties, although perhaps to a differentextent.

Thus, films of Group VIII metals and metal oxides, particularly thesecond and third row metals (e.g., Ru, Os, Rh, Ir, Pd, and Pt) havesuitable properties for a variety of uses in integrated circuits. Forexample, they can be used in integrated circuits for electricalcontacts. They are particularly suitable for use as barrier layersbetween the dielectric material and the silicon substrate in memorydevices, such as ferroelectric memories. Furthermore, they may even besuitable as the plate (i.e., electrode) itself in capacitors.

Platinum is one of the candidates for use as an electrode for highdielectric capacitors. Capacitors are the basic charge storage devicesin random access memory devices, such as dynamic random access memory(DRAM) devices, static random access memory (SRAM) devices, and nowferroelectric memory (FE RAM) devices. They consist of two conductors,such as parallel metal or polysilicon plates, which act as theelectrodes (i.e., the storage node electrode and the cell platecapacitor electrode), insulated from each other by a dielectric material(a ferroelectric dielectric material for FE RAMs). Thus, there is acontinuing need for methods and materials for the deposition of GroupVIII metal-containing films, preferably, platinum-containing films.

Many surfaces that result during the formation of Group VIIImetal-containing films, particularly in the wafer fabrication ofsemiconductor devices, do not have uniform height, and therefore, thewafer thickness is also non-uniform. Further, surfaces may have defectssuch as crystal lattice damage, scratches, roughness, or embeddedparticles of dirt or dust. For various fabrication processes to beperformed, such as lithography and etching, height non-uniformities anddefects at the surface of the wafer must be reduced or eliminated.Various planarization techniques are available to provide such reductionand/or elimination. One such planarization technique includes mechanicaland/or chemical-mechanical polishing (abbreviated herein as “CMP”).

The process of planarization is used to remove material, and preferablyachieve a planar surface, over the entire chip and wafer, sometimesreferred to as “global planarity.” Conventionally, the process ofplanarization, and particularly CMP, involves the use of a wafer holderthat holds a wafer, a polishing pad, and an abrasive slurry thatincludes a dispersion of a plurality of abrasive particles in a liquid.The abrasive slurry is applied so that it contacts the interface of thewafer and the polishing pad. A table or platen has a polishing padthereon. The polishing pad is applied to the wafer at a certain pressureto perform the planarization. At least one of the wafer and a polishingpad are set in motion relative to the other. In some planarizationprocesses, the wafer holder may or may not rotate, the table or platenmay or may not rotate and/or the platen may be moved in a linear motionas opposed to rotating. There are numerous types of planarization unitsavailable which perform the process in different manners. Alternatively,the polishing pad and abrasive slurry may be replaced by a fixedabrasive article that includes a plurality of abrasive particlesdispersed within a binder adhered to at least one surface of a backingmaterial.

The planarization of a surface that includes platinum and other GroupVIII metals typically involves mechanical polishing, as opposed tochemical-mechanical polishing, because they are relatively chemicallyinert and/or have relatively few volatile products. Such mechanicalpolishing uses alumina and silica particles. Unfortunately, mechanicalpolishing tends to cause smearing (i.e., undesirable relocation oftarget material, particularly ductile materials) and the formation ofdefects (e.g., scratches), both of which can be detected optically,rather than the clean removal of the platinum. Also, many commerciallyavailable abrasive slurries do not effectively planarize platinum orother Group VIII metal-containing surfaces either because no material isremoved (which results in no change in resistance of the wafer) or theresultant surface has defects therein.

Another process for removing material is etching. Etching is theselective removal of material, either locally by masking an area or overan entire surface without masking, the latter of which is referred to asblanket etching. Typically, wet etching is performed by immersing thesubstrate in an appropriate solution or by spraying the surface with theetchant solution. Etchants used for platinum include aqua regia (amixture of nitric acid and hydrochloric acid); however, this does notgenerally etch alloys of platinum, particularly platinum-rhodium.Compositions that do etch alloys such as platinum-rhodium includecompounds that are not compatible with other fabrication processesand/or are difficult to apply. These include KMnO₄ and zinc powder, forexample.

Thus, there is still a need for methods for planarizing or etching anexposed surface of a substrate that includes Group VIII metals,particularly in the fabrication of semiconductor devices.

SUMMARY OF THE INVENTION

The present invention provides methods that overcome many of theproblems associated with the removal of a material from a surface thatincludes one or more Group VIII metals, preferably platinum andoptionally another of the Group VIII metals. Such a surface is referredto herein as a Group VIII metal-containing surface. Preferably, a “GroupVIII metal-containing surface” refers to an exposed region having aGroup VIII metal (preferably platinum) present in an amount of at leastabout 50 atomic percent of the composition of the region. Morepreferably, the surface includes (and most preferably, consistsessentially of) platinum in elemental form or an alloy with one or moreother Group VIII metals. That is, the surface does not includesignificant amounts of non-Group VIII metals or nonmetals such assilicon, oxygen, or nitrogen atoms. Most preferably, the surfaceincludes a platinum/rhodium alloy present in an amount of at least about60 atomic percent platinum and no more than about 40 atomic percentrhodium.

The material may be provided as a layer, film, coating, etc. Preferably,it is removed via planarization (e.g., via chemical-mechanical ormechanical planarization or polishing) or etching, in accordance withthe present invention.

The methods of the present invention involve removing the Group VIIImetal-containing material using an acidic composition that includes amixture of phosphoric acid, sulfuric acid, nitric acid, and hydrochloricacid. This mixture can be used in wet etching or planarizationprocesses. The workpiece can be immersed in the acidic composition orthe acidic composition can be sprayed on the workpiece.

Preferably, the acidic composition, which can be in the form of anetchant solution or acidic composition, includes a mixture of phosphoricacid, sulfuric acid, nitric acid, and hydrochloric acid. Typically, anamount of each is used in excess of the target material to be removed.

In preferred embodiments, the acidic composition includes phosphoricacid initially in an amount of at least about 10 vol-% and no greaterthan about 25 vol-%, sulfuric acid initially in an amount of at leastabout 10 vol-% and no greater than about 50 vol-%, nitric acid initiallyin an amount of at least about 0.25 vol-% and no greater than about 10vol-%, and hydrochloric acid initially in an amount of at least about 25vol-% and no greater than about 50 vol-%. More preferably, the nitricacid is initially present in an amount of at least about 0.25 vol-% andno greater than about 1 vol-%.

The acidic composition can optionally include abrasive particles,thereby resulting in an abrasive slurry, and be used in planarizationtechniques with conventional polishing pads that do not have abrasiveparticles embedded therein. Alternatively, the acidic compositionwithout abrasive particles therein can be used with fixed abrasivearticles (i.e., abrasive polishing pads) in place of conventionalpolishing pads. Such fixed abrasive articles include a plurality ofabrasive particles dispersed within a binder adhered to at least onesurface of a backing material. Whether in a fixed abrasive or in theacidic composition, preferred abrasive particles have a hardness of nogreater than about 9 mho. If the acidic composition is not stable incombination with abrasive particles (i.e., an abrasive slurry), they maybe provided by separate delivery systems and/or in separate compositionsand mixed at the point of use.

Thus, in one aspect of the present invention, a method is providedwherein contacting the Group VIII metal-containing material with anacidic composition involves: positioning the Group VIII metal-containingsurface of the substrate to interface with a polishing pad; supplying anacidic composition in proximity to the interface; and planarizing thesubstrate surface. The acidic composition can include a plurality ofabrasive particles and/or the polishing pad can include a plurality ofabrasive particles.

As used herein, “semiconductor substrate or substrate assembly” refersto a semiconductor substrate such as a base semiconductor layer or asemiconductor substrate having one or more layers, structures, orregions formed thereon. A base semiconductor layer is typically thelowest layer of silicon material on a wafer or a silicon layer depositedon another material, such as silicon on sapphire. When reference is madeto a substrate assembly, various process steps may have been previouslyused to form or define regions, junctions, various structures orfeatures, and openings such as vias, contact openings, high aspect ratioopenings, conductive regions, contact regions, etc. For example, asubstrate assembly may refer to a structure upon which a metallizationis to be performed, e.g., metal lines are formed for electricalinterconnection functionality.

Herein, as is conventionally understood, “wet etching” or simply“etching” refers to the removal of material from a surface, whether itbe a large or small amount of material, using chemical dissolution.Typically, wet etching is performed by immersing the substrate in anappropriate solution or by spraying the surface with the etchantsolution.

Herein, as is conventionally understood, “planarizing” or“planarization” refers to the removal of material from a surface,whether it be a large or small amount of material, either mechanically,chemically, or both. This also includes removing material by polishing.As used herein, “chemical-mechanical polishing” and “CMP” refer to adual mechanism having both a chemical component and a mechanicalcomponent, wherein corrosion chemistry and fracture mechanics both playa roll in the removal of material, as in wafer polishing.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B are cross-sectional illustrations of one portion of awafer before and after an etching or planarization process has beenperformed in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides methods of removing material, either byetching or by planarization, from a surface that includes one or more ofthe Group VIII metals. The Group VIII metals are also referred to as theGroup VIIIB elements or transition metals of Groups 8, 9, and 10 of thePeriodic Table, and include the iron triad (Fe, Ru, Os), the cobalttriad (Co, Rh, Ir), and the nickel triad (Ni, Pd, Pt). Such a surface isreferred to herein as a Group VIII metal-containing surface.

The planarization of such surfaces, particularly a surface that includesplatinum in elemental form, typically involves mechanical methods withrelatively hard particles such as alumina (Al₂O₃) and silica (SiO₂)particles, which can cause smearing and the formation of defects ratherthan the clean removal of the material. Surprisingly, the use of anacidic composition as described herein in combination with a pluralityof abrasive particles in the composition or with a fixed abrasivearticle reduces, and often eliminates (depending on the processingconditions), the problems of smearing and defect formation. Similarly,the etching of such surfaces using an acidic composition as describedherein is much more acceptable and effective than conventional etchingsolutions.

Significantly, the methods of the present invention are particularlyadvantageous in removing platinum optionally in combination with otherGroup VIII metals from a surface in preference to other elements, suchas oxides, silicides, and nitrides. This is important in selectivelyremoving material from Group VIII metal-containing layers withoutremoving, for example, significant amounts of underlying layers, such asoxide layers (e.g., TEOS or BPSG layers) and other dielectric layers.

Preferably, the acidic composition, which can be in the form of anetchant solution or acidic composition, includes a mixture of phosphoricacid (H₃PO₄), sulfuric acid (H₂SO₄), nitric acid (HNO₃), andhydrochloric acid (HCl). Each of these acids is typically available inan aqueous solution. Thus, the acidic composition is typically anaqueous composition, whether additional water is added or not. Ifdesired, additional deionized water (e.g., of the level of purityconventionally used in semiconductor processing) can be added.

The acidic composition is defined herein in terms of the amounts ofconcentrated acids used. Commercially available concentratedreagent-grade phosphoric acid is typically a 14.7 Normal solution andincludes about 85 wt-% phosphoric acid. Commercially availableconcentrated reagent-grade sulfuric acid is typically a 36 Normalsolution and includes about 96 wt-% to about 98 wt-% sulfuric acid.Commercially available concentrated reagent-grade nitric acid istypically a 15.9 Normal solution and includes about 70 wt-% nitric acid.Commercially available concentrated reagent-grade hydrochloric acid istypically a 12 Normal solution and includes about 37 wt-% to about 38wt-% hydrochloric acid.

The phosphoric acid is preferably present in the composition initially(i.e., added as a concentrated solution) in an amount of at least about10 volume percent (vol-%), and preferably no greater than about 25vol-%. The sulfuric acid is preferably present in the compositioninitially (i.e., added as a concentrated solution) in an amount of atleast about 10 vol-%, and preferably no greater than about 50 vol-%. Thenitric acid is preferably present in the composition initially (i.e.,added as a concentrated solution) in an amount of at least about 0.25vol-%, and preferably no greater than about 10 vol-% (more preferably,no greater than about 1 vol-%, particularly for platinum-rhodium alloys,and most preferably, no greater than about 0.5 vol-%). The hydrochloricacid is preferably present in the composition initially (i.e., added asa concentrated solution) in an amount of at least about 25 vol-%, andpreferably no greater than about 50 vol-%. For certain preferredembodiments, the acids are combined as concentrated solutions in amountsas follows: at least about 10 vol-% phosphoric acid, at least about 10vol-% sulfuric acid, no greater than about 10 vol-% (more preferably, nogreater than about 1 vol-%, and most preferably, no greater than about0.5 vol-%) nitric acid, and at least about 25 vol-% hydrochloric acid. Apreferred composition for removing platinum includesH₃PO₄:H₂SO₄:HCl:HNO₃ in relative amounts of about 25:25:50:8 by volumeof concentrated acids. A preferred composition for removingplatinum/rhodium (preferably an alloy of at least 60 atomic percentplatinum and no greater than about 40 atomic percent rhodium) includesH₃PO₄:H₂SO₄:HCl:HNO₃in relative amounts of about 25:25:50:0.5 by volumeof concentrated acids.

The acidic composition is preferably used at an elevated temperature.Typically, the acidic composition is used at a temperature of at leastabout 65° C., and preferably, at a temperature of at least about 80° C.Typically, a temperature of no greater than about 100° C. is used. Ifthe temperature is less than about 65° C., the removal rate is typicallytoo slow and nonuniform for practical application. If the temperature ismore than about 100° C., the composition is typically too unstable.

Preferably, the acidic composition of the present invention is preparedin a manner to prevent hazardous exotherms. A preferred order of mixingis as follows: phosphoric acid is added to sulfuric acid, which resultsin an exotherm of about 60° C.; hydrochloric acid is then added to themixture of phosphoric and sulfuric acids, which cools the mixture downto about 40° C. because of a slight endotherm between the hydrochloricacid and the sulfuric acid; the mixture is then heated to at least about65° C. and nitric acid is added.

The acidic composition can be used in slurry planarization (i.e., in aconventional planarization process in which the acidic compositionincludes the abrasive particles with a polishing pad that does notinclude abrasive particles) or in fixed abrasive planarization.Preferably, slurry planarization is used in the methods of the presentinvention. Preferably, when used in slurry planarization, the acidiccomposition (i.e., abrasive slurry) includes the abrasive particles inan amount of about 1% by weight to about 30% by weight, and morepreferably, about 1% by weight to about 15% by weight.

A wide variety of abrasive particles can be used either in an abrasiveslurry or in a fixed abrasive article. Typically, such abrasiveparticles range in particle size (i.e., the largest dimension of theparticle) on average from about 10 nanometers (nm) to about 5000 nm, andmore often about 30 nm to about 1000 nm. For preferred embodiments,suitable abrasive particles have an average particle size of about 100nm to about 300 nm.

Examples of suitable abrasive particles include, but are not limited to,alumina (Al₂O₃), silica (SiO₂), ceria (CeO₂), yttria (Y₂O₃), zirconia(ZrO₂), and tantalum pentoxide (TaO₅). Preferred abrasive particlesinclude alumina (Al₂O₃), silica (SiO₂), ceria (CeO₂), and zirconia(ZrO₂). Various combinations of abrasive particles can be used ifdesired.

Preferably, for certain embodiments, abrasive particles include thosethat have a hardness of no greater than about 9 Mohs, and morepreferably no less than about 6 Mohs. These include, for example, ceria(CeO₂), which has a hardness of about 6 Mohs, alumina (Al₂O₃), which hasa hardness of about 9 Mohs, and silica (Si₂O₃), which has a hardness ofabout 7 Mohs.

For various desired effects, other additives can be included as well fordesired effects. These include, but are not limited to, a surfactant(e.g., polyethylene glycol, polyoxy ethylene ether, or polypropyleneglycol) to enhance wettability and reduce friction, a thickener (e.g.,CARBOPOL) to achieve a desired viscosity, etc. Preferably, thecomposition is an aqueous solution of these components.

For certain embodiments, the acidic composition includes a plurality ofabrasive particles. For other embodiments, the acidic composition isessentially free of abrasive particles when supplied to the interface ofthe fixed abrasive article and the workpiece surface. However, in theselatter embodiments, it is contemplated that planarization isaccomplished by one or both of the fixed abrasive article and/orabrasive particles that may be removed from the fixed abrasive articleat the fixed abrasive/surface interface in combination with the acidiccomposition. In any event, abrasive particles are typically not presentin the composition as initially applied, i.e., they are not suppliedfrom a source external to the polishing interface.

Various planarization assemblies or units for performing methods of theinvention are readily available and are clearly contemplated by thescope of the present invention as described in the accompanying claims.Such planarization assemblies can create an interface between apolishing pad or a fixed abrasive article and the substrate surface(e.g., wafer surface) in various manners, e.g., rotation, movement,pressure, etc., to achieve planarization. An acidic composition istypically introduced at or near the interface, by a variety of methodssuch as by dripping, spraying, or other dispensing means, or bypresoaking a polishing pad, although other locations and methods ofintroduction can be used.

In a typical planarizing machine, a polishing pad or fixed abrasivearticle is fixed on a platen or table, a carrier assembly that includesa substrate holder to support the substrate (e.g., wafer) typicallyusing suction, and a drive assembly to rotate and/or reciprocate theplaten and/or a drive assembly to rotate and/or translate the substrateholder during planarization. Thus, conventional planarizing machinesrotate the carrier assembly, the polishing pad or fixed abrasivearticle, or both the carrier assembly and the polishing pad or fixedabrasive article. In general, the planarizing machines are used toproduce a planarization reaction product at the surface of a substratewhose hardness is less than the hardness of the abrasive particles andwhose adhesion to the substrate is less than the original surfacematerial; and to remove the reaction produce using the abrasiveparticles.

Typically, the polishing pads, with or without abrasive particlesembedded therein, are disk-shaped and rotatable about a fixed plane andaxis at constant or variable speeds. Typically, the speed of rotationranges from about 2 revolutions per minute (rpm) to about 200 rpm.

Typically, a polishing pad is presoaked and continually rewet with theacidic composition. If the polishing pad does not include abrasiveparticles embedded therein, the acidic composition includes abrasiveparticles, which is then referred to as an abrasive slurry. The acidiccomposition may be applied to the interface between a polishing pad anda substrate surface using a variety of techniques. For example, thecomponent parts of the composition may be applied separately and mixedat the interface or immediately before contacting the interface. Theacidic composition can be applied by pumping it through the pad.Alternatively, it can be applied at the leading edge of the pad,although this may not provide uniform distribution of the acidiccomposition across the surface being planarized, which is desirable.

The polishing pad can be any of a wide variety of conventional polishingpads that are used with abrasive slurries. They can be made from amaterial such as polyurethane, polyester, acrylic, acrylic estercopolymers, polytetrafluoroethylene, polypropylene, polyethylene,cellulose, cellulose esters, polyamides, polyimides, polysiloxane,polycarbonates, epoxides, phenolic resins, etc. They include, forexample, a polyurethane-based foam material, wherein the foam cell wallsof the pad aid in removal of reaction products at the wafer surface andthe pores within the pad assist in supplying slurry to the pad/waferinterface. They can include convex or concave features, which can beformed by embossing a surface pattern. For example, a polishing pad canhave continuous grooves in concentric ellipses in the surface of the padfor more uniform slurry delivery and more effective debris removal.Commercially available polishing pads can be obtained under the tradedesignations “URII,” “Sycamore,” and “Polytex” from Rodel, Phoenix,Ariz. Examples of polishing pads are also disclosed in U.S. Pat. No.6,039,633 (Chopra).

In general, a fixed abrasive includes a plurality of abrasive particlesdispersed within a binder that forms a three-dimensional fixed abrasiveelement that is adhered to one surface of a backing material. They aredescribed, for example, in U.S. Pat. No. 5,692,950 (Rutherford, et al.)and International Patent Publication WO 98/06541. Commercially availablefixed abrasive articles can be obtained from Tokyo Sumitsu Kageki andEbera Corporation, both of Japan, and Minnesota Mining and ManufacturingCompany (3M Company) of St. Paul, Minn. An example of a preferred fixedabrasive article is a ceria-based pad commercially available from 3MCompany under the trade designation “SWR 159.” Such fixed abrasivearticles can be used with a acidic composition as described herein withor without abrasive particles in the acidic composition.

It is highly desirable to have a high polishing rate (i.e., the rate atwhich material is removed from the substrate) to reduce the duration ofeach planarizing cycle. Furthermore, it is highly desirable for thepolishing rate to be uniform across the substrate to produce a uniformlyplanar surface. Preferably, the polishing rate is controlled to provideaccurate, reproducible results. Also, preferably, the planarizationprocess is carried out in one cycle (i.e., one step). That is, for theremoval of any material from a particular surface, there is only oneplanarization cycle without any intervening rinse cycles. Thisplanarization process is then typically followed by a post-planarizationclean process in which abrasive particles are not used.

The figures provide further information about the methods of theinvention. FIG. 1A illustrates one portion of a wafer 10 prior toplanarization or etching in accordance with the present invention. Thewafer portion 10 includes a substrate assembly 12 having junctions 16formed thereon. Isolation areas can also be formed on substrate assembly12 having a patterned dielectric layer, e.g., an interlayer dielectricmaterial, formed thereon that can be used, for example, in the formationof an interconnect structure. The patterned dielectric layer may beformed of any layer providing electrical isolation between metalregions. For example, such a dielectric material may be a patternedoxide layer, e.g., silicon dioxide or TEOS (tetraethyl orthosilicate).

An interconnect material 19 is then formed over the substrate assembly12 and the patterned dielectric layer 16. The interconnect material 19may be any conductive material such as platinum or any other suitableconductive Group VIII metal-containing interconnect material. Generally,as shown in FIG. 1A, the nonplanar upper surface 13 of interconnectlayer 19 is subjected to planarization or etching in accordance with thepresent invention. Preferably, planarization is carried out such thatthe resulting wafer 10, as shown in FIG. 1B, includes an upper surface17 planarized so the thickness of the wafer 10 is substantially uniformacross the entire wafer 10. As a result, the wafer now includeselectrically conductive regions 19, isolated within the patterneddielectric material 16 forming an interconnect layer 14, e.g., theconductive lines of the interconnect structure is separated bydielectric material.

Further, as shown in FIG. 1B, the upper surface 17 of the interconnectlayer 14 includes both dielectric material surface regions 16′ andconductive surface regions 19′ such that no conductive material 19remains over the patterned dielectric layer 16.

FIG. 1A is shown only to illustrate a surface having nonuniformities,such as height differences, in the fabrication of semiconductor devices.The present invention is not limited to use with nonplanar surfaces,such as that shown in FIG. 1A. The present invention is also beneficialfor use with substantially planar surfaces. For example, the methods inaccordance with the present invention are beneficial during the wholeplanarization process, even at the end of the process when the surfacebeing planarized is in a substantially planar state. Furthermore, themethods in accordance with the present invention are beneficial duringetching processes, including damascene-type etching processes.

The following examples are offered to further illustrate the variousspecific and preferred embodiments and techniques. It should beunderstood, however, that many variations and modifications may be madewhile remaining within the scope of the present invention.

EXAMPLES

For removing 100% platinum, a typical method involves immersing aworkpiece with platinum thereon in a composition of H₃PO₄:H₂SO₄:HCl:HNO₃in relative amounts of about 25:25:50:8 by volume at 80° C. A typicaletch rate is about 600 Angstroms per minute.

For removing 60/40 Pt/Rh, a typical method involves immersing aworkpiece with Pt/Rh thereon in a composition of H₃PO₄:H₂SO₄:HCl:HNO₃ inrelative amounts of about 25:25:50:0.5 by volume at 80° C. A typicaletch rate is about 400 Angstroms per minute.

The foregoing detailed description and examples have been given forclarity of understanding only. No unnecessary limitations are to beunderstood therefrom. The invention is not limited to the exact detailsshown and described, for variations obvious to one skilled in the artwill be included within the invention defined by the claims. Thecomplete disclosures of all patents, patent documents, and publicationslisted herein are incorporated by reference, as if each wereindividually incorporated by reference.

1-28. (canceled)
 29. An acidic composition for removing a Group VIIImetal-containing material from a surface of a substrate, the compositioncomprising: phosphoric acid initially in an amount of at least about 10vol-% and no greater than about 25 vol-%; sulfuric acid initially in anamount of at least about 10 vol-% and no greater than about 50 vol-%;nitric acid initially in an amount of at least about 0.25 vol-% and nogreater than about 10 vol-%; and hydrochloric acid initially in anamount of at least about 25 vol-% and no greater than about 50 vol-%.30. The acidic composition of claim 29 wherein nitric acid is initiallypresent in an amount of at least about 0.25 vol-% and no greater thanabout 1 vol-%.
 31. The acidic composition of claim 29 further comprisinga plurality of abrasive particles.
 32. An acidic composition comprisinga mixture of concentrated acids without additional added water, themixture comprising: concentrated phosphoric acid; concentrated sulfuricacid; concentrated nitric acid; and concentrated hydrochloric acid. 33.The acidic composition of claim 32 wherein the composition is forremoving a Group VIII metal-containing material from a surface of asubstrate.
 34. The acidic composition of claim 32 further comprising aplurality of abrasive particles.
 35. The acidic composition of claim 32further comprising a substrate in contact with the mixture ofconcentrated acids, wherein the substrate has a Group VIIImetal-containing material on the surface thereof.
 36. The acidiccomposition of claim 35 wherein the Group VIII metal-containing materialis elemental platinum.
 37. The acidic composition of claim 35 whereinthe Group VIII metal-containing material is a platinum-rhodiumalloy-containing material.
 38. The acidic composition of claim 37wherein the platinum-rhodium alloy-containing material comprises atleast about 60 atomic percent platinum and no greater than about 40atomic percent rhodium.
 39. The acidic composition of claim 35 whereinthe substrate is a semiconductor substrate or substrate assembly. 40.The acidic composition of claim 39 wherein the semiconductor substrateor substrate assembly is a wafer.
 41. The acidic composition of claim 35wherein the substrate is immersed in the mixture of concentrated acids.42. The acidic composition of claim 35 wherein the mixture ofconcentrated acids is sprayed on the substrate.
 43. The acidiccomposition of claim 35 wherein the phosphoric acid is present in thecomposition initially in an amount of at least about 10 vol-% and nogreater than about 25 vol-%.
 44. The acidic composition of claim 35wherein the sulfuric acid is present in the composition initially in anamount of at least about 10 vol-% and no greater than about 50 vol-%.45. The acidic composition of claim 35 wherein the nitric acid ispresent in the composition initially in an amount of at least about 0.25vol-% and no greater than about 10 vol-%.
 46. The acidic composition ofclaim 35 wherein the nitric acid is present in the composition initiallyin an amount of at least about 0.25 vol-% and no greater than about 1vol-%.
 47. The acidic composition of claim 35 wherein the hydrochloricacid is present in the composition initially in an amount of at leastabout 25 vol-% and no greater than about 50 vol-%.
 48. An acidiccomposition for removing a Group VIII metal-containing material from asurface of a substrate, the composition comprising a mixture ofconcentrated acids without additional added water, the mixturecomprising: concentrated phosphoric acid initially in an amount of atleast about 10 vol-% and no greater than about 25 vol-%; concentratedsulfuric acid initially in an amount of at least about 10 vol-% and nogreater than about 50 vol-%; concentrated nitric acid initially in anamount of at least about 0.25 vol-% and no greater than about 10 vol-%;and concentrated hydrochloric acid initially in an amount of at leastabout 25 vol-% and no greater than about 50 vol-%.
 49. The acidiccomposition of claim 48 wherein nitric acid is initially present in anamount of at least about 0.25 vol-% and no greater than about 1 vol-%.50. The acidic composition of claim 48 further comprising a plurality ofabrasive particles.
 51. The acidic composition of claim 48 wherein themixture of concentrated acids is at a temperature of at least about 65°C.
 52. The acidic composition of claim 51 wherein the mixture ofconcentrated acids at a temperature of no greater than about 100° C. 53.The acidic composition of claim 48 wherein the mixture of concentratedacids is at a temperature of at least about 80° C.
 54. The acidiccomposition of claim 53 wherein the mixture of concentrated acids at atemperature of no greater than about 100° C.